In this technical field, methods and apparatuses which enable the integration of the production of the tire reinforcements in the assembly of the tire itself are already known. This means that, rather than resorting to semi-finished products, such as reinforcement plies, one or more reinforcements are constructed in situ at the time when the tire is produced and from a single thread reel. Among these methods and apparatuses, the solution described in U.S. Pat. No. 5,616,209 is very particularly suitable for the construction of carcass reinforcements on a rigid core, the outer surface of which corresponds substantially to the form of the inner cavity of the final tire. The '209 patent discloses an apparatus in which the thread intended to form a carcass reinforcement is laid in contiguous hoops on a rigid core by an eyelet fixed on a chain mounted on pulleys so as to surround the core by forming a kind of “C” shape. The eyelet performs a to-and-fro movement about the core so as to lay, progressively and contiguously, one hoop on each outward journey and one hoop on each return journey, with the intervention of appropriate pressers for applying the ends of the hoops to the rigid core, precoated with crude rubber, in the process.
An apparatus likewise provided for the construction of carcass reinforcements on a rigid core, the outer surface of which corresponds substantially to the form of the inner cavity of the final tire, is known from the European Patent Application EP 0 962 304. This document discloses, in a first embodiment, a single oscillating arm, the end of which, supporting a guiding member comparable to the eyelet mentioned above, necessarily describes circular arcs. Reference may be made to FIG. 3 of the Patent Application EP 0 962 304. The problem which arises is that if it is desired to operate at rapid laying rates, it is advisable that the extent of the characteristic angles and radii of the circular arc described is not too large. It is also advisable that the ends of the circular arc are not too far away from the bead, that is to say, the effective thread laying zone. Otherwise, the result would be harder work for the presser members and/or greater imprecision of the thread laying. If the geometrical axis of rotation of the oscillating arm is moved away towards the largest radii, the arm can skirt round the core without striking it. This promotes laying precision, but the circular arc described then becomes much larger (both in terms of angle and radius) and it is more difficult to operate at high rates. In summary, the important operating parameters are the position of the center of rotation of the oscillating arm, the swept angle, the radius of the arm, and the clearance which the arm must have with respect to the form over its entire length and in every operational spatial position.
In a second embodiment of the Patent Application EP 0 962 304, there can be seen a system with a cam and multiple articulated oscillating arms, the end supporting a guiding member which is comparable to the eyelet mentioned above, and which this time is held permanently in contact with the core. Reference may be made to FIG. 5 of the Patent Application EP 0 962 304. The problem which arises is that such a device exhibits a lot of friction, and that it might cause disruption, especially in the products made of crude rubber already laid on the surface of the core, which would be all the more extensive since one would be seeking to operate at high rates.
The object of the present invention is to propose apparatuses capable of operating according to the general method described in the above-mentioned U.S. Pat. No. 5,616,209, and capable of operating at considerable rates without having a detrimental effect on the operating precision.